Implementing incremental backup

24 files changed, 446 insertions, 257 deletions

diff --git a/lib/hamcrest-core-1.3.jar b/lib/hamcrest-core-1.3.jar
new file mode 100644
index 0000000..9d5fe16
--- /dev/null
+++ b/lib/hamcrest-core-1.3.jar
diff --git a/lib/junit-4.12.jar b/lib/junit-4.12.jar
new file mode 100644
index 0000000..3a7fc26
--- /dev/null
+++ b/lib/junit-4.12.jar
diff --git a/src/main/java/com/keuin/kbackupfabric/KBCommands.java b/src/main/java/com/keuin/kbackupfabric/KBCommands.java
index 9568842..bc04291 100644
--- a/src/main/java/com/keuin/kbackupfabric/KBCommands.java
+++ b/src/main/java/com/keuin/kbackupfabric/KBCommands.java
@@ -1,14 +1,16 @@
 package com.keuin.kbackupfabric;
 
-import com.keuin.kbackupfabric.metadata.BackupMetadata;
 import com.keuin.kbackupfabric.metadata.MetadataHolder;
 import com.keuin.kbackupfabric.operation.BackupOperation;
 import com.keuin.kbackupfabric.operation.DeleteOperation;
 import com.keuin.kbackupfabric.operation.RestoreOperation;
 import com.keuin.kbackupfabric.operation.abstracts.i.Invokable;
 import com.keuin.kbackupfabric.operation.backup.BackupMethod;
+import com.keuin.kbackupfabric.operation.backup.IncrementalBackupMethod;
+import com.keuin.kbackupfabric.operation.backup.PrimitiveBackupMethod;
 import com.keuin.kbackupfabric.util.backup.BackupFilesystemUtil;
-import com.keuin.kbackupfabric.util.backup.BackupNameSuggestionProvider;
+import com.keuin.kbackupfabric.util.backup.BackupType;
+import com.keuin.kbackupfabric.util.backup.suggestion.BackupNameSuggestionProvider;
 import com.keuin.kbackupfabric.util.backup.BackupNameTimeFormatter;
 import com.keuin.kbackupfabric.util.PrintUtil;
 import com.mojang.brigadier.arguments.StringArgumentType;
@@ -27,11 +29,13 @@ public final class KBCommands {
 
     private static final int SUCCESS = 1;
     private static final int FAILED = -1;
+    private static final String DEFAULT_BACKUP_NAME = "noname";
 
     //private static final Logger LOGGER = LogManager.getLogger();
 
     private static final List<String> backupNameList = new ArrayList<>(); // index -> backupName
     private static Invokable pendingOperation = null;
+    //private static BackupMethod activatedBackupMethod = new PrimitiveBackupMethod(); // The backup method we currently using
 
     /**
      * Print the help menu.
@@ -41,12 +45,12 @@ public final class KBCommands {
      */
     public static int help(CommandContext<ServerCommandSource> context) {
         msgInfo(context, "==== KBackup Manual ====");
-        msgInfo(context, "/kb       /kb help        Print help menu.");
-        msgInfo(context, "/kb list                  Show all backups.");
-        msgInfo(context, "/kb backup [backup_name]  Backup the whole level to backup_name. The default name is current system time.");
-        msgInfo(context, "/kb restore <backup_name> Delete the whole current level and restore from given backup. /kb restore is identical with /kb list.");
-        msgInfo(context, "/kb confirm               Confirm and start restoring.");
-        msgInfo(context, "/kb cancel                Cancel the restoration to be confirmed. If cancelled, /kb confirm will not run.");
+        msgInfo(context, "/kb , /kb help - Print help menu.");
+        msgInfo(context, "/kb list - Show all backups.");
+        msgInfo(context, "/kb backup [incremental/zip] [backup_name] - Backup the whole level to backup_name. The default name is current system time.");
+        msgInfo(context, "/kb restore <backup_name> - Delete the whole current level and restore from given backup. /kb restore is identical with /kb list.");
+        msgInfo(context, "/kb confirm - Confirm and start restoring.");
+        msgInfo(context, "/kb cancel - Cancel the restoration to be confirmed. If cancelled, /kb confirm will not run.");
         return SUCCESS;
     }
 
@@ -103,7 +107,7 @@ public final class KBCommands {
      * @param context the context.
      * @return stat code.
      */
-    public static int backup(CommandContext<ServerCommandSource> context) {
+    public static int primitiveBackup(CommandContext<ServerCommandSource> context) {
         //KBMain.backup("name")
         String backupName = StringArgumentType.getString(context, "backupName");
         if (backupName.matches("[0-9]*")) {
@@ -111,7 +115,32 @@ public final class KBCommands {
             backupName = String.format("a%s", backupName);
             msgWarn(context, String.format("Pure numeric name is not allowed. Renaming to %s", backupName));
         }
-        return doBackup(context, backupName, BackupMethod);
+        return doBackup(context, backupName, PrimitiveBackupMethod.getInstance());
+    }
+
+    /**
+     * Backup with default name.
+     *
+     * @param context the context.
+     * @return stat code.
+     */
+    public static int primitiveBackupWithDefaultName(CommandContext<ServerCommandSource> context) {
+        return doBackup(context, DEFAULT_BACKUP_NAME, PrimitiveBackupMethod.getInstance());
+    }
+
+    public static int incrementalBackup(CommandContext<ServerCommandSource> context) {
+        //KBMain.backup("name")
+        String backupName = StringArgumentType.getString(context, "backupName");
+        if (backupName.matches("[0-9]*")) {
+            // Numeric param is not allowed
+            backupName = String.format("a%s", backupName);
+            msgWarn(context, String.format("Pure numeric name is not allowed. Renaming to %s", backupName));
+        }
+        return doBackup(context, backupName, IncrementalBackupMethod.getInstance());
+    }
+
+    public static int incrementalBackupWithDefaultName(CommandContext<ServerCommandSource> context) {
+        return doBackup(context, DEFAULT_BACKUP_NAME, IncrementalBackupMethod.getInstance());
     }
 
     /**
@@ -168,6 +197,9 @@ public final class KBCommands {
             return FAILED;
         }
 
+        // Detect backup type
+
+
         // Update pending task
         //pendingOperation = AbstractConfirmableOperation.createRestoreOperation(context, backupName);
         File backupFile = new File(getBackupSaveDirectory(server), getBackupFileName(backupName));
@@ -177,17 +209,6 @@ public final class KBCommands {
         return SUCCESS;
     }
 
-
-    /**
-     * Backup with default name.
-     *
-     * @param context the context.
-     * @return stat code.
-     */
-    public static int backupWithDefaultName(CommandContext<ServerCommandSource> context) {
-        return doBackup(context, "noname");
-    }
-
     private static int doBackup(CommandContext<ServerCommandSource> context, String customBackupName, BackupMethod backupMethod) {
         // Real backup name (compatible with legacy backup): date_name, such as 2020-04-23_21-03-00_test
         //KBMain.backup("name")
@@ -287,6 +308,26 @@ public final class KBCommands {
         return SUCCESS;
     }
 
+    /**
+     * Select the backup method we use.
+     * @param context the context.
+     * @return stat code.
+     */
+    public static int setMethod(CommandContext<ServerCommandSource> context) {
+        String desiredMethodName = StringArgumentType.getString(context, "backupMethod");
+        List<BackupType> backupMethods = Arrays.asList(BackupType.PRIMITIVE_ZIP_BACKUP, BackupType.OBJECT_TREE_BACKUP);
+        for (BackupType method : backupMethods) {
+            if(method.getName().equals(desiredMethodName)) {
+                // Incremental backup
+//                activatedBackupMethod =
+                msgInfo(context, String.format("Backup method is set to: %s", desiredMethodName));
+                return SUCCESS;
+            }
+        }
+
+        return SUCCESS;
+    }
+
 
     private static String parseBackupName(CommandContext<ServerCommandSource> context, String userInput) {
         try {
diff --git a/src/main/java/com/keuin/kbackupfabric/KBCommandRegister.java b/src/main/java/com/keuin/kbackupfabric/KBCommandsRegister.java
index bfbe3c1..3376ac9 100644
--- a/src/main/java/com/keuin/kbackupfabric/KBCommandRegister.java
+++ b/src/main/java/com/keuin/kbackupfabric/KBCommandsRegister.java
@@ -1,13 +1,14 @@
 package com.keuin.kbackupfabric;
 
-import com.keuin.kbackupfabric.util.backup.BackupNameSuggestionProvider;
+import com.keuin.kbackupfabric.util.backup.suggestion.BackupMethodSuggestionProvider;
+import com.keuin.kbackupfabric.util.backup.suggestion.BackupNameSuggestionProvider;
 import com.keuin.kbackupfabric.util.PermissionValidator;
 import com.mojang.brigadier.CommandDispatcher;
 import com.mojang.brigadier.arguments.StringArgumentType;
 import net.minecraft.server.command.CommandManager;
 import net.minecraft.server.command.ServerCommandSource;
 
-public final class KBCommandRegister {
+public final class KBCommandsRegister {
     // First make method to register
     public static void registerCommands(CommandDispatcher<ServerCommandSource> dispatcher) {
 
@@ -18,8 +19,24 @@ public final class KBCommandRegister {
         // register /kb list for showing the backup list. OP is required.
         dispatcher.register(CommandManager.literal("kb").then(CommandManager.literal("list").requires(PermissionValidator::op).executes(KBCommands::list)));
 
+        // register /kb backup zip [name] as a alias
+        dispatcher.register(CommandManager.literal("kb").then(CommandManager.literal("backup").then(
+                CommandManager.literal("zip").then(
+                        CommandManager.argument("backupName", StringArgumentType.greedyString()).requires(PermissionValidator::op).executes(KBCommands::primitiveBackup)
+                ).requires(PermissionValidator::op).executes(KBCommands::primitiveBackupWithDefaultName)))
+        );
+
+        // register /kb backup incremental [name]
+        dispatcher.register(CommandManager.literal("kb").then(CommandManager.literal("backup").then(
+                CommandManager.literal("incremental").then(
+                        CommandManager.argument("backupName", StringArgumentType.greedyString()).requires(PermissionValidator::op).executes(KBCommands::incrementalBackup)
+                ).requires(PermissionValidator::op).executes(KBCommands::incrementalBackupWithDefaultName)))
+        );
+
         // register /kb backup [name] for performing backup. OP is required.
-        dispatcher.register(CommandManager.literal("kb").then(CommandManager.literal("backup").then(CommandManager.argument("backupName", StringArgumentType.greedyString()).requires(PermissionValidator::op).executes(KBCommands::backup)).requires(PermissionValidator::op).executes(KBCommands::backupWithDefaultName)));
+        dispatcher.register(CommandManager.literal("kb").then(CommandManager.literal("backup").then(
+                CommandManager.argument("backupName", StringArgumentType.greedyString()).requires(PermissionValidator::op).executes(KBCommands::primitiveBackup)
+        ).requires(PermissionValidator::op).executes(KBCommands::primitiveBackupWithDefaultName)));
 
         // register /kb restore <name> for performing restore. OP is required.
         dispatcher.register(CommandManager.literal("kb").then(CommandManager.literal("restore").then(CommandManager.argument("backupName", StringArgumentType.greedyString()).suggests(BackupNameSuggestionProvider.getProvider()).requires(PermissionValidator::op).executes(KBCommands::restore)).executes(KBCommands::list)));
@@ -35,5 +52,8 @@ public final class KBCommandRegister {
 
         // register /kb prev for showing the latest backup.
         dispatcher.register(CommandManager.literal("kb").then(CommandManager.literal("prev").requires(PermissionValidator::op).executes(KBCommands::prev)));
+
+        // register /kb setMethod for selecting backup method (zip, incremental)
+        dispatcher.register(CommandManager.literal("kb").then(CommandManager.literal("setMethod").then(CommandManager.argument("backupMethod", StringArgumentType.string()).suggests(BackupMethodSuggestionProvider.getProvider()).requires(PermissionValidator::op).executes(KBCommands::setMethod))));
     }
 }
diff --git a/src/main/java/com/keuin/kbackupfabric/KBPluginEvents.java b/src/main/java/com/keuin/kbackupfabric/KBPluginEvents.java
index d67d85b..3cb2dbe 100644
--- a/src/main/java/com/keuin/kbackupfabric/KBPluginEvents.java
+++ b/src/main/java/com/keuin/kbackupfabric/KBPluginEvents.java
@@ -3,7 +3,7 @@ package com.keuin.kbackupfabric;
 import com.keuin.kbackupfabric.metadata.BackupMetadata;
 import com.keuin.kbackupfabric.metadata.MetadataHolder;
 import com.keuin.kbackupfabric.util.backup.BackupFilesystemUtil;
-import com.keuin.kbackupfabric.util.backup.BackupNameSuggestionProvider;
+import com.keuin.kbackupfabric.util.backup.suggestion.BackupNameSuggestionProvider;
 import com.keuin.kbackupfabric.util.PrintUtil;
 import net.fabricmc.api.ModInitializer;
 import net.fabricmc.fabric.api.event.server.ServerStartCallback;
@@ -30,7 +30,7 @@ public final class KBPluginEvents implements ModInitializer, ServerStartCallback
     @Override
     public void onInitialize() {
         System.out.println("Binding events and commands ...");
-        CommandRegistry.INSTANCE.register(false, KBCommandRegister::registerCommands);
+        CommandRegistry.INSTANCE.register(false, KBCommandsRegister::registerCommands);
         ServerStartCallback.EVENT.register(this);
     }
 
@@ -58,7 +58,7 @@ public final class KBPluginEvents implements ModInitializer, ServerStartCallback
 
                 // Print metadata
                 MetadataHolder.setMetadata(metadata);
-                PrintUtil.info("Restored from a previous backup:");
+                PrintUtil.info("Restored world from a previous backup:");
                 PrintUtil.info("Backup Name: " + metadata.getBackupName());
                 PrintUtil.info("Create Time: " + (new SimpleDateFormat("yyyy-MM-dd HH:mm:ss")).format(new Date(metadata.getBackupTime())));
 
diff --git a/src/main/java/com/keuin/kbackupfabric/Random.java b/src/main/java/com/keuin/kbackupfabric/Random.java
deleted file mode 100644
index e87e4c1..0000000
--- a/src/main/java/com/keuin/kbackupfabric/Random.java
+++ /dev/null
@@ -1,97 +0,0 @@
-package com.keuin.kbackupfabric;
-
-import java.util.ArrayList;
-import java.util.LinkedList;
-import java.util.List;
-
-public class Random {
-    public int random(int A, int B) {
-        return (int) (A + (B - A + 1) * Math.random());
-    }
-
-    public double[] randomArray(int MaxN, int lowA, int highA) {
-        double[] array = new double[random(1,MaxN)];
-        for (int i = 0; i < array.length; i++) {
-            array[i] = lowA + (highA - lowA) * Math.random();
-        }
-        return array;
-    }
-
-    public double[] generate(int MaxN, int lowA, int highA) {
-        double[] testData = randomArray(MaxN,lowA,highA);
-        double x = testData[random(0,testData.length-1)];
-    }
-
-    public int R(double[] a, double x) {
-        List<Integer> list = new LinkedList<>();
-        int k;
-        for (int i = 0; i < a.length; i++) {
-            if(Math.abs(a[i] - x) < 1e-6)
-                list.add(i);
-        }
-        assert !list.isEmpty();
-        k = list.get(list.size() / 2);
-        return k;
-    }
-
-
-    public boolean domR(double[] a, double x) {
-        for (double v : a) {
-            if(Math.abs(v - x) < 1e-6)
-                return true;
-        }
-        return false;
-    }
-
-    public boolean oracle(double[] a, double x, int k) {
-        if(!(Math.abs(a[k] - x) < 1e-6))
-            return false;
-        int c1=0,c2=0;
-        for (int i = 0; i < k; i++) {
-            if(Math.abs(a[i] - x) < 1e-6)
-                ++c1;
-        }
-        for (int i = k; i < a.length; i++) {
-            if(Math.abs(a[i] - x) < 1e-6)
-                ++c2;
-        }
-        return c1 - c2 >= -1 && c1 - c2 <= 1;
-    }
-
-    public boolean driver() {
-        int MaxN = 80, lowA = 20, highA = 50;
-        double[] a = randomArray(MaxN,lowA,highA);
-        double x = a[random(0,a.length-1)];
-        return oracle(a,x,search(a,x));
-    }
-
-
-    public int search(double[] a, double x) {
-        int counter = 0;
-        for (double i : a) {
-            if(Math.abs(i - x) < 1e-6)
-                ++counter;
-        }
-        counter /= 2;
-        for (int i = 0; i < a.length; i++) {
-            if(Math.abs(a[i] - x) < 1e-6) {
-                --counter;
-                if(counter == 0)
-                    return i;
-            }
-        }
-        return -1;
-    }
-
-    public static void Main() {
-        int pass = 0, fail = 0;
-        for (int i = 0; i < 10000; i++) {
-            if(driver())
-                pass++;
-            else
-                fail++;
-        }
-        System.out.println(String.format("pass: %d, fail: %d.",pass,fail));
-    }
-
-}
diff --git a/src/main/java/com/keuin/kbackupfabric/operation/BackupOperation.java b/src/main/java/com/keuin/kbackupfabric/operation/BackupOperation.java
index 071726b..d03c347 100644
--- a/src/main/java/com/keuin/kbackupfabric/operation/BackupOperation.java
+++ b/src/main/java/com/keuin/kbackupfabric/operation/BackupOperation.java
@@ -8,7 +8,6 @@ import com.keuin.kbackupfabric.util.PrintUtil;
 import com.keuin.kbackupfabric.util.backup.builder.BackupFileNameBuilder;
 import com.keuin.kbackupfabric.util.backup.formatter.BackupFileNameFormatter;
 import com.mojang.brigadier.context.CommandContext;
-import com.sun.istack.internal.NotNull;
 import net.minecraft.server.MinecraftServer;
 import net.minecraft.server.command.ServerCommandSource;
 import net.minecraft.world.World;
@@ -30,7 +29,7 @@ public class BackupOperation extends InvokableAsyncBlockingOperation {
     private long startTime;
 
 
-    public BackupOperation(@NotNull CommandContext<ServerCommandSource> context, @NotNull String backupName, @NotNull BackupMethod backupMethod, @NotNull BackupFileNameBuilder backupFileNameBuilder, @NotNull BackupFileNameFormatter backupFileNameFormatter) {
+    public BackupOperation(CommandContext<ServerCommandSource> context, String backupName, BackupMethod backupMethod) {
         super("BackupWorker");
         this.context = context;
         this.backupName = backupName;
@@ -56,7 +55,8 @@ public class BackupOperation extends InvokableAsyncBlockingOperation {
             String levelPath = getLevelPath(server);
             String backupFileName = getBackupFileName(backupName);
 
-            if(backupMethod.backup(backupName,levelPath,backupSaveDirectory)) {
+            BackupMethod.BackupResult result = backupMethod.backup(backupName,levelPath,backupSaveDirectory);
+            if(result.isSuccess()) {
                 // Restore old autosave switch stat
                 server.getWorlds().forEach(world -> world.savingDisabled = oldWorldsSavingDisabled.getOrDefault(world, true));
 
@@ -64,10 +64,7 @@ public class BackupOperation extends InvokableAsyncBlockingOperation {
                 long timeElapsedMillis = System.currentTimeMillis() - startTime;
                 String msgText = String.format("Backup finished. Time elapsed: %.2fs.", timeElapsedMillis / 1000.0);
                 File backupZipFile = new File(backupSaveDirectory, backupFileName);
-                try {
-                    msgText += String.format(" File size: %s.", humanFileSize(backupZipFile.length()));
-                } catch (SecurityException ignored) {
-                }
+                msgText += String.format(" File size: %s.", humanFileSize(result.getBackupSizeBytes()));
                 PrintUtil.msgInfo(context, msgText, true);
             } else {
                 // failed
diff --git a/src/main/java/com/keuin/kbackupfabric/operation/DeleteOperation.java b/src/main/java/com/keuin/kbackupfabric/operation/DeleteOperation.java
index 30fdfc0..444ca9a 100644
--- a/src/main/java/com/keuin/kbackupfabric/operation/DeleteOperation.java
+++ b/src/main/java/com/keuin/kbackupfabric/operation/DeleteOperation.java
@@ -1,7 +1,7 @@
 package com.keuin.kbackupfabric.operation;
 
 import com.keuin.kbackupfabric.operation.abstracts.InvokableAsyncBlockingOperation;
-import com.keuin.kbackupfabric.util.backup.BackupNameSuggestionProvider;
+import com.keuin.kbackupfabric.util.backup.suggestion.BackupNameSuggestionProvider;
 import com.keuin.kbackupfabric.util.PrintUtil;
 import com.mojang.brigadier.context.CommandContext;
 import net.minecraft.server.MinecraftServer;
diff --git a/src/main/java/com/keuin/kbackupfabric/operation/RestoreOperation.java b/src/main/java/com/keuin/kbackupfabric/operation/RestoreOperation.java
index ef6ab2b..22397a1 100644
--- a/src/main/java/com/keuin/kbackupfabric/operation/RestoreOperation.java
+++ b/src/main/java/com/keuin/kbackupfabric/operation/RestoreOperation.java
@@ -84,54 +84,21 @@ public class RestoreOperation extends InvokableBlockingOperation {
                     }
                 }
 
-                PrintUtil.info("Wait for 5 seconds ...");
-                try {
-                    Thread.sleep(5000);
-                } catch (InterruptedException ignored) {
-                }
-
-                // Delete old level
-                PrintUtil.info("Server stopped. Deleting old level ...");
-                File levelDirFile = new File(levelDirectory);
-                long startTime = System.currentTimeMillis();
-
-                int failedCounter = 0;
-                final int MAX_RETRY_TIMES = 20;
-                while (failedCounter < MAX_RETRY_TIMES) {
-                    System.gc();
-                    if (!levelDirFile.delete() && levelDirFile.exists()) {
-                        System.gc();
-                        forceDelete(levelDirFile); // Try to force delete.
-                    }
-                    if (!levelDirFile.exists())
-                        break;
-                    ++failedCounter;
-                    try {
-                        Thread.sleep(500);
+                int cnt = 5;
+                do {
+                    PrintUtil.info(String.format("Wait %d seconds ...", cnt));
+                    try{
+                        Thread.sleep(1000);
                     } catch (InterruptedException ignored) {
                     }
-                }
-                if (levelDirFile.exists()) {
-                    PrintUtil.error(String.format("Cannot restore: failed to delete old level %s .", levelDirFile.getName()));
-                    return;
-                }
+                }while(--cnt > 0);
 
-                // Decompress archive
-                PrintUtil.info("Decompressing archived level ...");
-                ZipUtil.unzip(backupFilePath, levelDirectory, false);
-                long endTime = System.currentTimeMillis();
-                PrintUtil.info(String.format("Restore complete! (%.2fs) Please restart the server manually.", (endTime - startTime) / 1000.0));
-                PrintUtil.info("If you want to restart automatically after restoring, please visit the project manual at: https://github.com/keuin/KBackup-Fabric/blob/master/README.md");
-
-                try {
-                    Thread.sleep(1000);
-                } catch (InterruptedException ignored) {
-                }
+                ////////////////////
 
                 //ServerRestartUtil.forkAndRestart();
                 System.exit(111);
 
-            } catch (SecurityException | IOException | ZipUtilException e) {
+            } catch (SecurityException e) {
                 PrintUtil.error("An exception occurred while restoring: " + e.getMessage());
             }
         }
diff --git a/src/main/java/com/keuin/kbackupfabric/operation/backup/BackupMethod.java b/src/main/java/com/keuin/kbackupfabric/operation/backup/BackupMethod.java
index b0b77cb..4e9eb6c 100644
--- a/src/main/java/com/keuin/kbackupfabric/operation/backup/BackupMethod.java
+++ b/src/main/java/com/keuin/kbackupfabric/operation/backup/BackupMethod.java
@@ -2,10 +2,12 @@ package com.keuin.kbackupfabric.operation.backup;
 
 import com.keuin.kbackupfabric.util.backup.builder.BackupFileNameBuilder;
 import com.keuin.kbackupfabric.util.backup.formatter.BackupFileNameFormatter;
-import com.sun.istack.internal.NotNull;
 
 import java.io.IOException;
 
+/**
+ * Provide specific backup method, which is implemented statelessly.
+ */
 public interface BackupMethod {
 
     /**
@@ -14,10 +16,29 @@ public interface BackupMethod {
      * @param backupName the backup name.
      * @return if the backup operation succeed.
      */
-    boolean backup(@NotNull String backupName, @NotNull String levelPath, @NotNull String backupSaveDirectory) throws IOException;
+    BackupResult backup(String backupName, String levelPath, String backupSaveDirectory) throws IOException;
+
+    boolean restore(String backupName, String levelPath, String backupSaveDirectory) throws IOException;
 
     BackupFileNameBuilder getBackupFileNameBuilder();
 
     BackupFileNameFormatter getBackupFileNameFormatter();
 
+    class BackupResult {
+        private final boolean success;
+        private final long backupSizeBytes;
+
+        public BackupResult(boolean success, long backupSizeBytes) {
+            this.success = success;
+            this.backupSizeBytes = backupSizeBytes;
+        }
+
+        public boolean isSuccess() {
+            return success;
+        }
+
+        public long getBackupSizeBytes() {
+            return backupSizeBytes;
+        }
+    }
 }
diff --git a/src/main/java/com/keuin/kbackupfabric/operation/backup/IncrementalBackupMethod.java b/src/main/java/com/keuin/kbackupfabric/operation/backup/IncrementalBackupMethod.java
new file mode 100644
index 0000000..4a87bb3
--- /dev/null
+++ b/src/main/java/com/keuin/kbackupfabric/operation/backup/IncrementalBackupMethod.java
@@ -0,0 +1,62 @@
+package com.keuin.kbackupfabric.operation.backup;
+
+import com.google.gson.JsonObject;
+import com.keuin.kbackupfabric.util.PrintUtil;
+import com.keuin.kbackupfabric.util.backup.builder.BackupFileNameBuilder;
+import com.keuin.kbackupfabric.util.backup.builder.ObjectTreeBackupFileNameBuilder;
+import com.keuin.kbackupfabric.util.backup.formatter.BackupFileNameFormatter;
+import com.keuin.kbackupfabric.util.backup.formatter.ObjectTreeBackupFileNameFormatter;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Paths;
+import java.time.LocalDateTime;
+
+public class IncrementalBackupMethod implements BackupMethod {
+
+    private static final IncrementalBackupMethod INSTANCE = new IncrementalBackupMethod();
+
+    public static IncrementalBackupMethod getInstance() {
+        return INSTANCE;
+    }
+
+    @Override
+    public BackupResult backup(String backupName, String levelPath, String backupSaveDirectory) throws IOException {
+        /*
+        1. Analyze the save directory, to get a json containing md5 values of all files.
+        2. Copy new files which we do not have in our backup repository.
+        3. Save the above json as a backup file. When restoring from this,
+           what we have to do is just copy all files back from the repository,
+           based on their md5 digests.
+         */
+
+        boolean success = true;
+        // Generate JSON
+        JsonObject hashJson = IncrementalBackupUtil.generateDirectoryJsonObject(levelPath);
+        // Copy files
+        long newFilesSizeBytes = IncrementalBackupUtil.saveNewFiles(backupSaveDirectory, levelPath, hashJson);
+        if(newFilesSizeBytes < 0) {
+            success = false;
+            PrintUtil.error("Failed to copy new files to object tree.");
+        }
+        // Save JSON tree
+        File jsonFile = new File(String.valueOf(Paths.get(backupSaveDirectory, BackupFileNameBuilder.objectTreeBackup().build(LocalDateTime.now(), backupName))));
+        // TODO
+        return new BackupResult(success, newFilesSizeBytes);
+    }
+
+    @Override
+    public boolean restore(String backupName, String levelPath, String backupSaveDirectory) throws IOException {
+        return false;
+    }
+
+    @Override
+    public BackupFileNameBuilder getBackupFileNameBuilder() {
+        return null;
+    }
+
+    @Override
+    public BackupFileNameFormatter getBackupFileNameFormatter() {
+        return null;
+    }
+}
diff --git a/src/main/java/com/keuin/kbackupfabric/operation/backup/IncrementalBackupUtil.java b/src/main/java/com/keuin/kbackupfabric/operation/backup/IncrementalBackupUtil.java
new file mode 100644
index 0000000..f90aef1
--- /dev/null
+++ b/src/main/java/com/keuin/kbackupfabric/operation/backup/IncrementalBackupUtil.java
@@ -0,0 +1,90 @@
+package com.keuin.kbackupfabric.operation.backup;
+
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import com.keuin.kbackupfabric.util.FilesystemUtil;
+import org.apache.commons.codec.digest.DigestUtils;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.file.*;
+import java.util.Map;
+
+public class IncrementalBackupUtil {
+    /**
+     * Generate a json object representing a directory and its all sub files and directories.
+     * @param path path to the directory.
+     * @return a json object.
+     */
+    public static JsonObject generateDirectoryJsonObject(String path) throws IOException {
+        JsonObject json = new JsonObject();
+        File directory = new File(path);
+        if (!(directory.isDirectory() && directory.exists()))
+            throw new IOException(String.format("Path %s is not a valid directory.", path));
+
+        // Iterate all sub files using BFS.
+        try (DirectoryStream<Path> directoryStream = Files.newDirectoryStream(Paths.get(path))) {
+            for (Path sub : directoryStream) {
+                if (sub.toFile().isFile()) {
+                    // A sub file
+                    // Just hash and add it as a string
+                    try (InputStream is = Files.newInputStream(sub)) {
+                        String md5 = org.apache.commons.codec.digest.DigestUtils.md5Hex(is);
+                        json.addProperty(sub.getFileName().toString(), md5);
+                    }
+                } else {
+                    // A sub directory
+                    // Search into
+                    json.addProperty(String.valueOf(sub.getFileName()), sub.toString());
+                }
+            }
+        }
+
+        return json;
+    }
+
+    /**
+     * Save new (or modified) files to target path, based on hash json.
+     * @param targetSavePath where we should save new files.
+     * @param sourcePath where new files come from. This path must be the base directory of given hash json.
+     * @param hashJson the json object obtained by calling generateDirectoryJsonObject method.
+     * @return total size of new files. If failed, will return -1.
+     */
+    public static long saveNewFiles(String targetSavePath, String sourcePath, JsonObject hashJson) throws IOException {
+        long bytesCopied = 0;
+        for (Map.Entry<String, JsonElement> entry : hashJson.entrySet()) {
+            String key = entry.getKey();
+            JsonElement value = entry.getValue();
+            if (value.isJsonPrimitive() && value.getAsJsonPrimitive().isString()) {
+                // A sub file
+                // key is file name
+                // value is file md5
+                String md5 = value.getAsJsonPrimitive().getAsString();
+                File saveTarget = new File(targetSavePath, md5);
+                if (!saveTarget.exists()) {
+                    // Target file does not exist. We have to copy this to the target.
+                    File sourceFile = new File(sourcePath, key);
+                    Files.copy(sourceFile.toPath(), saveTarget.toPath(), StandardCopyOption.REPLACE_EXISTING, StandardCopyOption.COPY_ATTRIBUTES);
+                    try {
+                        bytesCopied += sourceFile.length();
+                    } catch (SecurityException ignored) {
+                        // failed to get the file size. Just ignore this.
+                    }
+                }
+            } else if (value.isJsonObject()) {
+                // A sub directory
+                // key is directory name
+                // value is directory json object
+                // Go into
+                if(!value.isJsonObject())
+                    throw new IllegalArgumentException(String.format("Hash json contains illegal argument of a directory item: %s -> %s.", key, value));
+                Path pathSource = Paths.get(sourcePath, key);
+                bytesCopied += saveNewFiles(targetSavePath, pathSource.toString(), value.getAsJsonObject());
+            } else {
+                throw new IllegalArgumentException(String.format("Hash json contains illegal element: %s -> %s.", key, value));
+            }
+        }
+        return bytesCopied;
+    }
+}
diff --git a/src/main/java/com/keuin/kbackupfabric/operation/backup/PrimitiveBackupMethod.java b/src/main/java/com/keuin/kbackupfabric/operation/backup/PrimitiveBackupMethod.java
index bb1c8cb..854355d 100644
--- a/src/main/java/com/keuin/kbackupfabric/operation/backup/PrimitiveBackupMethod.java
+++ b/src/main/java/com/keuin/kbackupfabric/operation/backup/PrimitiveBackupMethod.java
@@ -2,6 +2,7 @@ package com.keuin.kbackupfabric.operation.backup;
 
 import com.keuin.kbackupfabric.exception.ZipUtilException;
 import com.keuin.kbackupfabric.metadata.BackupMetadata;
+import com.keuin.kbackupfabric.util.FilesystemUtil;
 import com.keuin.kbackupfabric.util.PrintUtil;
 import com.keuin.kbackupfabric.util.ZipUtil;
 import com.keuin.kbackupfabric.util.backup.builder.BackupFileNameBuilder;
@@ -9,14 +10,23 @@ import com.keuin.kbackupfabric.util.backup.formatter.BackupFileNameFormatter;
 
 import java.io.File;
 import java.io.IOException;
-import java.time.LocalDate;
+import java.nio.file.Paths;
 import java.time.LocalDateTime;
 
+import static org.apache.commons.io.FileUtils.forceDelete;
+
 public class PrimitiveBackupMethod implements BackupMethod {
+
+    private static final PrimitiveBackupMethod INSTANCE = new PrimitiveBackupMethod();
+
+    public static PrimitiveBackupMethod getInstance() {
+        return INSTANCE;
+    }
+
     @Override
-    public boolean backup(String backupName, String levelPath, String backupSaveDirectory) throws IOException {
+    public BackupResult backup(String backupName, String levelPath, String backupSaveDirectory) throws IOException {
+        String backupFileName = BackupFileNameBuilder.primitiveZipBackup().build(LocalDateTime.now(),backupName);
         try {
-            String backupFileName = BackupFileNameBuilder.primitiveZipBackup().build(LocalDateTime.now(),backupName);
             BackupMetadata backupMetadata = new BackupMetadata(System.currentTimeMillis(), backupName);
 
             PrintUtil.info(String.format("zip(srcPath=%s, destPath=%s)", levelPath, backupSaveDirectory));
@@ -25,8 +35,54 @@ public class PrimitiveBackupMethod implements BackupMethod {
 
         } catch (ZipUtilException exception) {
             PrintUtil.info("Infinite recursive of directory tree detected, backup was aborted.");
+            return new BackupResult(false, 0);
+        }
+
+        // Get backup file size and return
+        return new BackupResult(true, FilesystemUtil.getFileSizeBytes(backupSaveDirectory, backupFileName));
+    }
+
+    @Override
+    public boolean restore(String backupName, String levelDirectory, String backupSaveDirectory) throws IOException {
+        // Delete old level
+        PrintUtil.info("Server stopped. Deleting old level ...");
+        File levelDirFile = new File(levelDirectory);
+        long startTime = System.currentTimeMillis();
+
+        int failedCounter = 0;
+        final int MAX_RETRY_TIMES = 20;
+        while (failedCounter < MAX_RETRY_TIMES) {
+            System.gc();
+            if (!levelDirFile.delete() && levelDirFile.exists()) {
+                System.gc();
+                forceDelete(levelDirFile); // Try to force delete.
+            }
+            if (!levelDirFile.exists())
+                break;
+            ++failedCounter;
+            try {
+                Thread.sleep(500);
+            } catch (InterruptedException ignored) {
+            }
+        }
+        if (levelDirFile.exists()) {
+            PrintUtil.error(String.format("Cannot restore: failed to delete old level %s .", levelDirFile.getName()));
             return false;
         }
+
+        // TODO: Refactor this to the concrete BackupMethod.
+        // Decompress archive
+        PrintUtil.info("Decompressing archived level ...");
+        ZipUtil.unzip(Paths.get(backupSaveDirectory, backupName).toString(), levelDirectory, false);
+        long endTime = System.currentTimeMillis();
+        PrintUtil.info(String.format("Restore complete! (%.2fs) Please restart the server manually.", (endTime - startTime) / 1000.0));
+        PrintUtil.info("If you want to restart automatically after restoring, please visit the project manual at: https://github.com/keuin/KBackup-Fabric/blob/master/README.md");
+
+//        try {
+//            Thread.sleep(1000);
+//        } catch (InterruptedException ignored) {
+//        }
+
         return true;
     }
 
@@ -37,6 +93,6 @@ public class PrimitiveBackupMethod implements BackupMethod {
 
     @Override
     public BackupFileNameFormatter getBackupFileNameFormatter() {
-        return BFNF;
+        return BackupFileNameFormatter.primitiveZipBackup();
     }
 }
diff --git a/src/main/java/com/keuin/kbackupfabric/util/FilesystemUtil.java b/src/main/java/com/keuin/kbackupfabric/util/FilesystemUtil.java
new file mode 100644
index 0000000..7f74725
--- /dev/null
+++ b/src/main/java/com/keuin/kbackupfabric/util/FilesystemUtil.java
@@ -0,0 +1,33 @@
+package com.keuin.kbackupfabric.util;
+
+import java.io.File;
+
+public class FilesystemUtil {
+
+    /**
+     * Get file sizes in bytes.
+     * @param parentDirectory path to specific file.
+     * @param fileName file name.
+     * @return bytes. If failed, return -1.
+     */
+    public static long getFileSizeBytes(String parentDirectory, String fileName) {
+        long fileSize = -1;
+        try{
+            File backupZipFile = new File(parentDirectory, fileName);
+            fileSize = backupZipFile.length();
+        } catch (SecurityException ignored){
+        }
+        return fileSize;
+    }
+
+    public static long getFileSizeBytes(String filePath) {
+        long fileSize = -1;
+        try{
+            File backupZipFile = new File(filePath);
+            fileSize = backupZipFile.length();
+        } catch (SecurityException ignored){
+        }
+        return fileSize;
+    }
+
+}
diff --git a/src/main/java/com/keuin/kbackupfabric/util/ServerRestartUtil.java b/src/main/java/com/keuin/kbackupfabric/util/ServerRestartUtil.java
deleted file mode 100644
index 1642e5c..0000000
--- a/src/main/java/com/keuin/kbackupfabric/util/ServerRestartUtil.java
+++ /dev/null
@@ -1,58 +0,0 @@
-package com.keuin.kbackupfabric.util;
-
-public class ServerRestartUtil {
-
-    public static void forkAndRestart() {
-//        Runtime.getRuntime().addShutdownHook(new Thread(new Runnable() {
-//            @Override
-//            public void run() {
-//                // Here we restart the minecraft server
-//                StringBuilder cmd = new StringBuilder();
-//                cmd.append(System.getProperty("java.home")).append(File.separator).append("bin").append(File.separator).append("java ");
-//                for (String jvmArg : ManagementFactory.getRuntimeMXBean().getInputArguments()) {
-//                    cmd.append(jvmArg + " ");
-//                }
-//                cmd.append("-cp ").append(ManagementFactory.getRuntimeMXBean().getClassPath()).append(" ");
-//                cmd.append(MinecraftServer.class.getName()).append(" ");
-//                for (String arg : args) {
-//                    cmd.append(arg).append(" ");
-//                }
-//                Runtime.getRuntime().exec(cmd.toString());
-//                System.exit(0);
-//            }
-//        }));
-    }
-
-    private static void startRestartThread() {
-//        (new Thread(() -> {
-//
-//
-//            // kill threads
-//            Set<Thread> threads = Thread.getAllStackTraces().keySet();
-//            Thread currentThread = Thread.currentThread();
-//            for (Thread t : threads) {
-//                if(t != currentThread && t.isAlive()) {
-//                    t.setUncaughtExceptionHandler((t1, e) -> {
-//                        // set empty handler
-//                    });
-//                    //t.interrupt();
-//                    try {
-//                        t.setDaemon(true);
-//                    } catch (Exception ignored) {
-//                    }
-//
-//                    t.stop();
-//                }
-//            }
-//
-//            try {
-//                Thread.sleep(5000);
-//            } catch (InterruptedException ignored) {
-//            }
-//
-//            // restart Minecraft server
-//            String[] args = new String[]{};
-//            MinecraftServer.main(args);
-//        })).start();
-    }
-}
diff --git a/src/main/java/com/keuin/kbackupfabric/util/ZipUtil.java b/src/main/java/com/keuin/kbackupfabric/util/ZipUtil.java
index 0ca8da3..c670cf1 100644
--- a/src/main/java/com/keuin/kbackupfabric/util/ZipUtil.java
+++ b/src/main/java/com/keuin/kbackupfabric/util/ZipUtil.java
@@ -147,9 +147,9 @@ public final class ZipUtil {
      * @param unzipFilePath      解压后的文件保存的路径
      * @param includeZipFileName 解压后的文件保存的路径是否包含压缩文件的文件名。true-包含；false-不包含
      */
-    public static void unzip(String zipFilePath, String unzipFilePath, boolean includeZipFileName) throws ZipUtilException, IOException {
+    public static void unzip(String zipFilePath, String unzipFilePath, boolean includeZipFileName) throws IOException {
         if (zipFilePath.isEmpty() || unzipFilePath.isEmpty()) {
-            throw new ZipUtilException("Parameter for unzip() contains null.");
+            throw new IllegalArgumentException("Parameter for unzip() contains null.");
         }
         File zipFile = new File(zipFilePath);
         // 如果解压后的文件保存路径包含压缩文件的文件名，则追加该文件名到解压路径
diff --git a/src/main/java/com/keuin/kbackupfabric/util/backup/BackupType.java b/src/main/java/com/keuin/kbackupfabric/util/backup/BackupType.java
index 95a32ae..d02ce77 100644
--- a/src/main/java/com/keuin/kbackupfabric/util/backup/BackupType.java
+++ b/src/main/java/com/keuin/kbackupfabric/util/backup/BackupType.java
@@ -4,18 +4,30 @@ package com.keuin.kbackupfabric.util.backup;
  * Representing the backup type.
  * Should only be used in BackupFileNameBuilder and BackupFileNameFormatter
  */
+@Deprecated
 public enum BackupType {
 
-    PRIMITIVE_ZIP_BACKUP("Primitive Zip Backup"),
-    OBJECT_TREE_BACKUP("Object Tree Backup");
+    PRIMITIVE_ZIP_BACKUP("Primitive Zip Backup", "zip"),
+    OBJECT_TREE_BACKUP("Object Tree Backup", "incremental");
 
-    private final String name;
-    BackupType(String name) {
+    private final String friendlyName; // e.g. Primitive Zip Backup
+    private final String name; // e.g. zip
+
+    BackupType(String friendlyName, String name) {
+        this.friendlyName = friendlyName;
         this.name = name;
     }
 
+    /**
+     * Get name used in command.
+     * @return name (such as "zip", "incremental").
+     */
+    public String getName() {
+        return name;
+    }
+
     @Override
     public String toString() {
-        return name;
+        return friendlyName;
     }
 }
diff --git a/src/main/java/com/keuin/kbackupfabric/util/backup/builder/BackupFileNameBuilder.java b/src/main/java/com/keuin/kbackupfabric/util/backup/builder/BackupFileNameBuilder.java
index 16c598b..f57302c 100644
--- a/src/main/java/com/keuin/kbackupfabric/util/backup/builder/BackupFileNameBuilder.java
+++ b/src/main/java/com/keuin/kbackupfabric/util/backup/builder/BackupFileNameBuilder.java
@@ -1,6 +1,5 @@
 package com.keuin.kbackupfabric.util.backup.builder;
 
-import com.sun.istack.internal.NotNull;
 
 import java.time.LocalDateTime;
 
@@ -20,6 +19,6 @@ public interface BackupFileNameBuilder {
      * @param backupName the custom name of this backup. Note that this should be a valid file name in current file system.
      * @return the backup file name string.
      */
-    String build(@NotNull LocalDateTime time, @NotNull String backupName);
+    String build(LocalDateTime time, String backupName);
 
 }
diff --git a/src/main/java/com/keuin/kbackupfabric/util/backup/formatter/BackupFileNameFormatter.java b/src/main/java/com/keuin/kbackupfabric/util/backup/formatter/BackupFileNameFormatter.java
index eae3639..a437629 100644
--- a/src/main/java/com/keuin/kbackupfabric/util/backup/formatter/BackupFileNameFormatter.java
+++ b/src/main/java/com/keuin/kbackupfabric/util/backup/formatter/BackupFileNameFormatter.java
@@ -1,7 +1,6 @@
 package com.keuin.kbackupfabric.util.backup.formatter;
 
 import com.keuin.kbackupfabric.util.backup.BackupNameTimeFormatter;
-import com.sun.istack.internal.NotNull;
 
 import java.time.LocalDateTime;
 import java.util.regex.Matcher;
@@ -9,7 +8,7 @@ import java.util.regex.Pattern;
 
 public interface BackupFileNameFormatter {
 
-    BackupFileName format(@NotNull String fileName);
+    BackupFileName format(String fileName);
 
     class BackupFileName {
         public final LocalDateTime time;
diff --git a/src/main/java/com/keuin/kbackupfabric/util/backup/formatter/ObjectTreeBackupFileNameFormatter.java b/src/main/java/com/keuin/kbackupfabric/util/backup/formatter/ObjectTreeBackupFileNameFormatter.java
index e5503a9..08805b2 100644
--- a/src/main/java/com/keuin/kbackupfabric/util/backup/formatter/ObjectTreeBackupFileNameFormatter.java
+++ b/src/main/java/com/keuin/kbackupfabric/util/backup/formatter/ObjectTreeBackupFileNameFormatter.java
@@ -2,8 +2,6 @@ package com.keuin.kbackupfabric.util.backup.formatter;
 
 import com.keuin.kbackupfabric.util.backup.BackupFilesystemUtil;
 import com.keuin.kbackupfabric.util.backup.BackupNameTimeFormatter;
-import com.sun.istack.internal.NotNull;
-import com.sun.istack.internal.Nullable;
 import org.spongepowered.asm.mixin.Overwrite;
 
 import java.time.LocalDateTime;
@@ -19,13 +17,12 @@ public class ObjectTreeBackupFileNameFormatter implements BackupFileNameFormatte
     }
 
     @Override
-    public BackupFileNameFormatter.BackupFileName format(@NotNull String fileName) {
+    public BackupFileNameFormatter.BackupFileName format(String fileName) {
         LocalDateTime time = getTime(fileName);
         String name = getBackupName(fileName);
         return new BackupFileNameFormatter.BackupFileName(time,name);
     }
 
-    @Nullable
     private LocalDateTime getTime(String fileName) {
         Matcher matcher = Pattern.compile("[0-9]{4}-[0-9]{2}-[0-9]{2}_[0-9]{2}-[0-9]{2}-[0-9]{2}").matcher(fileName);
         if (matcher.find()) {
diff --git a/src/main/java/com/keuin/kbackupfabric/util/backup/formatter/PrimitiveZipBackupFileNameFormatter.java b/src/main/java/com/keuin/kbackupfabric/util/backup/formatter/PrimitiveZipBackupFileNameFormatter.java
index 40450eb..2d50d17 100644
--- a/src/main/java/com/keuin/kbackupfabric/util/backup/formatter/PrimitiveZipBackupFileNameFormatter.java
+++ b/src/main/java/com/keuin/kbackupfabric/util/backup/formatter/PrimitiveZipBackupFileNameFormatter.java
@@ -2,8 +2,6 @@ package com.keuin.kbackupfabric.util.backup.formatter;
 
 import com.keuin.kbackupfabric.util.backup.BackupFilesystemUtil;
 import com.keuin.kbackupfabric.util.backup.BackupNameTimeFormatter;
-import com.sun.istack.internal.NotNull;
-import com.sun.istack.internal.Nullable;
 
 import java.time.LocalDateTime;
 import java.util.regex.Matcher;
@@ -18,13 +16,12 @@ public class PrimitiveZipBackupFileNameFormatter implements BackupFileNameFormat
     }
 
     @Override
-    public BackupFileNameFormatter.BackupFileName format(@NotNull String fileName) {
+    public BackupFileNameFormatter.BackupFileName format(String fileName) {
         LocalDateTime time = getTime(fileName);
         String name = getBackupName(fileName);
         return new BackupFileNameFormatter.BackupFileName(time,name);
     }
 
-    @Nullable
     private LocalDateTime getTime(String fileName) {
         Matcher matcher = Pattern.compile("[0-9]{4}-[0-9]{2}-[0-9]{2}_[0-9]{2}-[0-9]{2}-[0-9]{2}").matcher(fileName);
         if (matcher.find()) {
diff --git a/src/main/java/com/keuin/kbackupfabric/util/backup/suggestion/BackupMethodSuggestionProvider.java b/src/main/java/com/keuin/kbackupfabric/util/backup/suggestion/BackupMethodSuggestionProvider.java
new file mode 100644
index 0000000..320d9bf
--- /dev/null
+++ b/src/main/java/com/keuin/kbackupfabric/util/backup/suggestion/BackupMethodSuggestionProvider.java
@@ -0,0 +1,36 @@
+package com.keuin.kbackupfabric.util.backup.suggestion;
+
+import com.keuin.kbackupfabric.util.backup.BackupType;
+import com.mojang.brigadier.suggestion.SuggestionProvider;
+import com.mojang.brigadier.suggestion.Suggestions;
+import com.mojang.brigadier.suggestion.SuggestionsBuilder;
+import net.minecraft.server.command.ServerCommandSource;
+
+import java.util.Arrays;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Locale;
+import java.util.concurrent.CompletableFuture;
+
+public class BackupMethodSuggestionProvider {
+
+    private static final List<String> suggestions = Arrays.asList(
+            BackupType.OBJECT_TREE_BACKUP.getName(),
+            BackupType.PRIMITIVE_ZIP_BACKUP.getName()
+    ); // All backup methods
+
+    public static SuggestionProvider<ServerCommandSource> getProvider() {
+        return (context, builder) -> getCompletableFuture(builder);
+    }
+
+    private static CompletableFuture<Suggestions> getCompletableFuture(SuggestionsBuilder builder) {
+        String remaining = builder.getRemaining().toLowerCase(Locale.ROOT);
+        for (String string : suggestions) { // Iterate through the supplied list
+            if (string.toLowerCase(Locale.ROOT).startsWith(remaining)) {
+                builder.suggest(string); // Add every single entry to suggestions list.
+            }
+        }
+        return builder.buildFuture(); // Create the CompletableFuture containing all the suggestions
+    }
+
+}
diff --git a/src/main/java/com/keuin/kbackupfabric/util/backup/BackupNameSuggestionProvider.java b/src/main/java/com/keuin/kbackupfabric/util/backup/suggestion/BackupNameSuggestionProvider.java
index 4639e99..f6f4056 100644
--- a/src/main/java/com/keuin/kbackupfabric/util/backup/BackupNameSuggestionProvider.java
+++ b/src/main/java/com/keuin/kbackupfabric/util/backup/suggestion/BackupNameSuggestionProvider.java
@@ -1,5 +1,6 @@
-package com.keuin.kbackupfabric.util.backup;
+package com.keuin.kbackupfabric.util.backup.suggestion;
 
+import com.keuin.kbackupfabric.util.backup.BackupFilesystemUtil;
 import com.mojang.brigadier.suggestion.SuggestionProvider;
 import com.mojang.brigadier.suggestion.Suggestions;
 import com.mojang.brigadier.suggestion.SuggestionsBuilder;
diff --git a/src/test/java/IncrementalBackupUtilTest.java b/src/test/java/IncrementalBackupUtilTest.java
new file mode 100644
index 0000000..b050a91
--- /dev/null
+++ b/src/test/java/IncrementalBackupUtilTest.java
@@ -0,0 +1,16 @@
+import com.keuin.kbackupfabric.operation.backup.IncrementalBackupUtil;
+
+import java.io.IOException;
+
+public class IncrementalBackupUtilTest {
+
+    @org.junit.Test
+    public void generateDirectoryJsonObject() {
+        try {
+            System.out.println(IncrementalBackupUtil.generateDirectoryJsonObject("D:\\1"));
+        } catch (IOException exception) {
+            exception.printStackTrace();
+        }
+
+    }
+}
\ No newline at end of file